FLIGHT International,
10 October 1963
607
A LEADING FAMILY
OF ROTARY-WING
AIRCRAFT
By the Technical Editor
When Igor Sikorsky made his first intuitive attempts to fly the VS-300 in September 1939 he had no audience
other than a few company engineers and mechanics; but one of the onlookers took this photograph to record
the occasion. It shows the VS-300 with its wheels as far off the ground as the short tie-down cables (carrying
a tray full of weights) permit
Sikorsky Helicopters
ANY citizens of Stratford, Connecticut, and neighbouring
communities will consider that the indefinite article in the
subtitle above should be replaced by a definite "The."
But there was little derinke about the concept of the helicopter
when Igor I. Sikorsky began to build one in May 1909. In January
of that year 19-year-old Igor left his home in Kiev and went to live
in Paris in order to be amongst flying machines and their designers.
Sikorsky had for more than a year been intrigued by the possi
bility of building a flying machine capable of rising directly under
the thrust of a lifting screw, and he persevered at the project despite
the discouraging views of other flying men. In the event, the latter
proved to be right; but only by the slenderest of margins. The two
helicopters which Sikorsky built before the spring of 1910 both
cnme very close to lifting themselves with their creator on board.
Nevertheless, it was apparent to the young Russian that his
resources would be more profitably applied to the design and con
struction of fixed-wing aeroplanes.
For the next 29 years Sikorsky became renowned as an outstand
ing constructor of big aeroplanes. In March 1919 he emigrated to
the USA, and an indication of his strength of character is provided
by the fact that he forthwith began to design and make ambitious
aircraft despite that fact that America was then a land of surplus
aeroplanes, unemployed aircraft designers and bankrupt aircraft
manufacturers. Sikorsky not only founded a completely new
aircraft-manufacturing company but also continued to specialize
in large aircraft, which had been his forte ever since he built the
first successful four-engined machine in 1913.
By 1929 the Sikorsky Aviation Corporation was prosperous, and
Igor could look with pride on an unrivalled series of big land-
Planes, amphibians and flying boats which even then were being
used by various airlines—notably Pan American—to open up new
routes across the widest oceans. But when in that year his firm
became a subsidiary of United Aircraft he told the UAC manage
ment that he was once again working on the problems of the
eacopter. Nine years later he asked for permission to build one, an
°- got it.
UAC had by 1938 merged the Sikorsky and Chance Vought
~v|s,ons to form Vought-Sikorsky, and the helicopter received the
<f>ignation VS-300. Built in one corner of the factory at Stratford,
^onnecticut, it was completed in the late summer of 1939, and on
Ptember 14 Igor strapped himself in and started the Franklin flat.
°ur engine. He was well aware of the fact that the VS-300
was a very new beast which might well bite its owner, and the
ungainly contraption was tethered so that its wheels could only just
leave the ground. But leave the ground the wheels did; and the rest
was merely a matter of engineering exploration and improvement.
Lee S. Johnson, now general manager of the firm, draws atten
tion to the significance of this crude and noisy contrivance in these
words: "Before Igor Sikorsky flew the VS-300 there was no heli
copter industry; after he flew it, there was."
VS-300 Igor had never subscribed to side-by-side or tandem
lifting rotors, but considered that the best arrangement for a
helicopter was a single lifting rotor mechanically linked to a torque-
reacting rotor at the tail. No Sikorsky helicopter has yet departed
from this layout.
Another point to note is that helicopters are fundamentally
different from aeroplanes in mechanical, as well as aerodynamic,
aspects. Whereas the aeroplane consists basically of an essentially
static "airframe" in which the dynamic engines and systems are
installed, the helicopter is designed around a vital series of "dynamic
components": powerplant, gearboxes, shafting, bearings, rotors
and controls. Very early in the game Sikorsky saw that the key
development task is the perfection of these dynamic components,
around which any suitable structure could easily be arranged to
carry the payload.
Thus the VS-300 was a rig with which Sikorsky proved his first
set of dynamic components; and the fact that this historic craft
was completely rebuilt several times is a reflection not on its
designer's ability but on the fact that the VS-300 was a completely
new type of flying machine, based upon some classic aerofoil
theory but developed largely upon an empirical basis. Probably
more development work was done with it than with any other
flying machine ever built.
When it first appeared it consisted of a minimum airframe
incorporating a pilot seat mounted just in front of the engine.
The latter drove through vee-belts and a bevel box to the 28ft
three-blade rotor, with flapping hinges, and three-blade tail rotor.
The latter was mounted on a vee-braced tail arm which also carried
a large vertical surface hanging down from the boom and pivoted
to left or right in the rotor downwash to give yawing control.
Before long the back end was replaced by a much longer steel-
tube structure giving a greater tail-rotor moment arm, and the
sideways-rudder was eliminated. At the same time a new parallelo-